cleanup: rm JOBS symbol, POSIX signal ifdefs, waitpid(2) fallback

jobs.h defines the JOBS symbol that is set if the system is deemed
to support jobs control. This symbol was set if either SIGCHLD or
SIGCLD is a signal on the current system. There is no POSIX
compliant system made in recent decades that doesn't have SIGCHLD,
whereas SIGCLD is completely obsolete.

As expected, bit rot set in long ago; a test build of ksh with JOBS
disabled failed. It is not worth fixing.

All changed files:
- Remove JOBS symbol and corresponding fallbacks.
- Remove preprocessor checks for the following signal symbols that
  have been specified by POSIX for decaces: SIGCHLD, SIGHUP,
  SIGPIPE, SIGQUIT, SIGSTOP, SIGTSTP, SIGTTIN, SIGTTOU.
- Remove all checks for and references to the obsolete SIGCLD
  symbol (all systems have been using SIGCHLD instead for decades).

src/lib/libast/comp/waitpid.c:
- Removed. All POSIX-ish operating systems provide waitpid(2), so
  none of the fallback code has been used for many years.

src/cmd/ksh93/bltins/misc.c

@@ -2,7 +2,7 @@
 *                                                                      *
 *               This software is part of the ast package               *
 *          Copyright (c) 1982-2012 AT&T Intellectual Property          *
-*          Copyright (c) 2020-2022 Contributors to ksh 93u+m           *
+*          Copyright (c) 2020-2023 Contributors to ksh 93u+m           *
 *                      and is licensed under the                       *
 *                 Eclipse Public License, Version 2.0                  *
 *                                                                      *
@@ -143,10 +143,8 @@ int    b_exec(int argc,char *argv[], Shbltin_t *context)
 		pname = argv[0];
 		if(arg0)
 			argv[0] = arg0;
-#ifdef JOBS
 		if(job_close() < 0)
 			return(1);
-#endif /* JOBS */
 		/* if the main shell is about to be replaced, decrease SHLVL to cancel out a subsequent increase */
 		if(!sh.realsubshell)
 			(*SHLVL->nvalue.ip)--;
@@ -421,12 +419,11 @@ int    b_wait(int n,register char *argv[],Shbltin_t *context)
 	return(sh.exitval);
 }
 
-#ifdef JOBS
-#   if 0
+#if 0
     /* for the dictionary generator */
 	int    b_fg(int n,char *argv[],Shbltin_t *context){}
 	int    b_disown(int n,char *argv[],Shbltin_t *context){}
-#   endif
+#endif
 int    b_bg(register int n,register char *argv[],Shbltin_t *context)
 {
 	register int flag = **argv;
@@ -504,7 +501,6 @@ int    b_jobs(register int n,char *argv[],Shbltin_t *context)
 	job_wait((pid_t)0);
 	return(sh.exitval);
 }
-#endif
 
 /*
  * times command

src/cmd/ksh93/bltins/trap.c

@@ -2,7 +2,7 @@
 *                                                                      *
 *               This software is part of the ast package               *
 *          Copyright (c) 1982-2012 AT&T Intellectual Property          *
-*          Copyright (c) 2020-2022 Contributors to ksh 93u+m           *
+*          Copyright (c) 2020-2023 Contributors to ksh 93u+m           *
 *                      and is licensed under the                       *
 *                 Eclipse Public License, Version 2.0                  *
 *                                                                      *
@@ -219,16 +219,12 @@ int	b_kill(int argc,char *argv[],Shbltin_t *context)
 	register int sig=SIGTERM, flag=0, n;
 	int usemenu = 0;
 	NOT_USED(argc);
-#if defined(JOBS) && defined(SIGSTOP)
 	if(**argv == 's')	/* <s>top == kill -s STOP */
 	{
 		flag |= S_FLAG;
 		signame = "STOP";
 	}
 	while((n = optget(argv, **argv == 's' ? sh_optstop : sh_optkill))) switch(n)
-#else
-	while((n = optget(argv,sh_optkill))) switch(n)
-#endif /* defined(JOBS) && defined(SIGSTOP) */
 	{
 		case ':':
 			if((signame=argv[opt_info.index++]) && (sig=sig_number(signame+1))>=0)
@@ -298,7 +294,6 @@ int	b_kill(int argc,char *argv[],Shbltin_t *context)
 	return(sh.exitval);
 }
 
-#if defined(JOBS) && defined(SIGSTOP)
 /*
  * former default alias suspend='kill -s STOP $$'
  */
@@ -337,7 +332,6 @@ int	b_suspend(int argc,char *argv[],Shbltin_t *context)
 	}
 	return(0);
 }
-#endif /* defined(JOBS) && defined(SIGSTOP) */
 
 /*
  * Given the name or number of a signal return the signal number

src/cmd/ksh93/data/builtins.c

@@ -97,21 +97,13 @@ const struct shtable3 shtab_builtins[] =
 #else
 	"echo",		NV_BLTIN|BLT_ENV,		Bltin(echo),
 #endif /* SHOPT_ECHOPRINT */
-#ifdef JOBS
-#   ifdef SIGTSTP
 	"bg",		NV_BLTIN|BLT_ENV,		bltin(bg),
 	"fg",		NV_BLTIN|BLT_ENV|BLT_EXIT,	bltin(bg),
 	"disown",	NV_BLTIN|BLT_ENV,		bltin(bg),
 	"kill",		NV_BLTIN|BLT_ENV,		bltin(kill),
-#   else
-	"/bin/kill",	NV_BLTIN|BLT_ENV,		bltin(kill),
-#   endif	/* SIGTSTP */
 	"jobs",		NV_BLTIN|BLT_ENV,		bltin(jobs),
-#   ifdef SIGSTOP
 	"stop",		NV_BLTIN|BLT_ENV,		bltin(kill),
 	"suspend", 	NV_BLTIN|BLT_ENV,		bltin(suspend),
-#   endif	/* SIGSTOP */
-#endif	/* JOBS */
 	"false",	NV_BLTIN|BLT_ENV,		bltin(false),
 	"getopts",	NV_BLTIN|BLT_ENV,		bltin(getopts),
 #if SHOPT_MKSERVICE
@@ -1138,7 +1130,6 @@ _JOB_
 "[+SEE ALSO?\bps\b(1), \bjobs\b(1), \bkill\b(2), \bsignal\b(2)]"
 ;
 
-#if defined(JOBS) && defined(SIGSTOP)
 const char sh_optstop[] =
 "[-1c?\n@(#)$Id: stop (ksh 93u+m) 2020-06-22 $\n]"
 "[--catalog?" SH_DICT "]"
@@ -1174,7 +1165,6 @@ const char sh_optsuspend[] =
 "}"
 "[+SEE ALSO?\bkill\b(1)]"
 ;
-#endif /* defined(JOBS) && defined(SIGSTOP) */
 
 const char sh_optlet[]	=
 "[-1c?\n@(#)$Id: let (AT&T Research) 2000-04-02 $\n]"

src/cmd/ksh93/data/msg.c

@@ -146,24 +146,20 @@ const char is_talias[]		= "is a tracked alias for";
 const char is_function[]	= " is a function";
 const char is_ufunction[]	= " is an undefined function";
 const char e_autoloadfrom[]	= " (autoload from %s)";
-#ifdef JOBS
-#   ifdef SIGTSTP
-	const char e_newtty[]	= "Switching to new tty driver...";
-	const char e_oldtty[]	= "Reverting to old tty driver...";
-	const char e_no_start[]	= "Cannot start job control";
-#   endif /*SIGTSTP */
-    const char e_no_jctl[]	= "No job control";
-    const char e_terminate[]	= "You have stopped jobs";
-    const char e_done[]		= " Done";
-    const char e_nlspace[]	= "\n      ";
-    const char e_running[]	= " Running";
-    const char e_ambiguous[]	= "%s: Ambiguous";
-    const char e_jobsrunning[]	= "You have running jobs";
-    const char e_no_job[]	= "no such job";
-    const char e_no_proc[]	= "no such process";
-    const char e_badpid[]	= "%s: invalid process ID";
-    const char e_jobusage[]	= "%s: Arguments must be %%job or process IDs";
-#endif /* JOBS */
+const char e_newtty[]		= "Switching to new tty driver...";
+const char e_oldtty[]		= "Reverting to old tty driver...";
+const char e_no_start[]		= "Cannot start job control";
+const char e_no_jctl[]		= "No job control";
+const char e_terminate[]	= "You have stopped jobs";
+const char e_done[]		= " Done";
+const char e_nlspace[]		= "\n      ";
+const char e_running[]		= " Running";
+const char e_ambiguous[]	= "%s: Ambiguous";
+const char e_jobsrunning[]	= "You have running jobs";
+const char e_no_job[]		= "no such job";
+const char e_no_proc[]		= "no such process";
+const char e_badpid[]		= "%s: invalid process ID";
+const char e_jobusage[]		= "%s: Arguments must be %%job or process IDs";
 const char e_coredump[]		= "(coredump)";
 const char e_alphanum[]		= "[_[:alpha:]]*([_[:alnum:]])";
 const char e_devfdNN[]		= "/dev/fd/+([0-9])";

src/cmd/ksh93/data/signals.c

@@ -2,7 +2,7 @@
 *                                                                      *
 *               This software is part of the ast package               *
 *          Copyright (c) 1982-2012 AT&T Intellectual Property          *
-*          Copyright (c) 2020-2022 Contributors to ksh 93u+m           *
+*          Copyright (c) 2020-2023 Contributors to ksh 93u+m           *
 *                      and is licensed under the                       *
 *                 Eclipse Public License, Version 2.0                  *
 *                                                                      *
@@ -19,10 +19,6 @@
 #include	"defs.h"
 #include	"jobs.h"
 
-#if defined(SIGCLD) && !defined(SIGCHLD)
-#   define SIGCHLD	SIGCLD
-#endif
-
 #define VAL(sig,mode)	((sig+1)|((mode)<<SH_SIGBITS))
 #define TRAP(n)		(((n)|SH_TRAP)-1)
 
@@ -61,16 +57,7 @@ const struct shtable2 shtab_signals[] =
 	"CANCEL",	VAL(SIGCANCEL,SH_SIGIGNORE), 			S("Thread cancellation"),
 #endif /*SIGCANCEL */
 #ifdef SIGCHLD
-	"CHLD",		VAL(SIGCHLD,SH_SIGFAULT), 			S("Death of Child"),
-#   ifdef SIGCLD
-#	if SIGCLD!=SIGCHLD
-	    "CLD",	VAL(SIGCLD,SH_SIGFAULT),			S("Death of Child"),
-#	endif
-#   endif	/* SIGCLD */
-#else
-#   ifdef SIGCLD
-	"CLD",		VAL(SIGCLD,SH_SIGFAULT),			S("Death of Child"),
-#   endif	/* SIGCLD */
+	"CHLD",		VAL(SIGCHLD,SH_SIGFAULT), 			S("Child process terminated or stopped"),
 #endif	/* SIGCHLD */
 #ifdef SIGCONT
 	"CONT",		VAL(SIGCONT,SH_SIGIGNORE),			S("Stopped process continued"),
@@ -102,11 +89,7 @@ const struct shtable2 shtab_signals[] =
 #endif /* SIGGRANT */
 	"HUP",		VAL(SIGHUP,SH_SIGDONE),				S("Hangup"),
 	"ILL",		VAL(SIGILL,SH_SIGDONE),				S("Illegal instruction"),
-#ifdef JOBS
 	"INT",		VAL(SIGINT,SH_SIGINTERACTIVE),			S("Interrupt"),
-#else
-	"INT",		VAL(SIGINT,SH_SIGINTERACTIVE),			"",
-#endif /* JOBS */
 #ifdef SIGINFO
 	"INFO",		VAL(SIGINFO,SH_SIGIGNORE),			S("Information request"),
 #endif	/* SIGINFO */
@@ -148,11 +131,7 @@ const struct shtable2 shtab_signals[] =
 	"PHONE",	VAL(SIGPHONE,0),				S("Phone interrupt"),
 #endif	/* SIGPHONE */
 #ifdef SIGPIPE
-#ifdef JOBS
 	"PIPE",		VAL(SIGPIPE,SH_SIGDONE),			S("Broken Pipe"),
-#else
-	"PIPE",		VAL(SIGPIPE,SH_SIGDONE),	 		"",
-#endif /* JOBS */
 #endif /* SIGPIPE */
 #ifdef SIGPOLL
 	"POLL",		VAL(SIGPOLL,SH_SIGDONE),			S("Polling alarm"),
@@ -201,11 +180,7 @@ const struct shtable2 shtab_signals[] =
 	"THAW",		VAL(SIGTHAW,SH_SIGIGNORE),			S("Special signal used by CPR"),
 #endif	/* SIGTHAW */
 #ifdef SIGTINT
-#   ifdef JOBS
 	"TINT",		VAL(SIGTINT,0),					S("Interrupt"),
-#   else
-	"TINT",		VAL(SIGTINT,0),					"",
-#   endif /* JOBS */
 #endif	/* SIGTINT */
 #ifdef SIGTRAP
 	"TRAP",		VAL(SIGTRAP,SH_SIGDONE),			S("Trace/BPT trap"),

src/cmd/ksh93/include/builtins.h

@@ -78,16 +78,10 @@ extern int b_unset(int, char*[],Shbltin_t*);
 extern int b_unalias(int, char*[],Shbltin_t*);
 
 /* The following are for job control */
-#if defined(SIGCLD) || defined(SIGCHLD)
-    extern int b_jobs(int, char*[],Shbltin_t*);
-    extern int b_kill(int, char*[],Shbltin_t*);
-#   ifdef SIGTSTP
-	extern int b_bg(int, char*[],Shbltin_t*);
-#   endif	/* SIGTSTP */
-#   ifdef SIGSTOP
-	extern int b_suspend(int, char*[],Shbltin_t*);
-#   endif	/* SIGSTOP */
-#endif
+extern int b_jobs(int, char*[],Shbltin_t*);
+extern int b_kill(int, char*[],Shbltin_t*);
+extern int b_bg(int, char*[],Shbltin_t*);
+extern int b_suspend(int, char*[],Shbltin_t*);
 
 /* The following utilities are built-in because of side-effects */
 extern int b_builtin(int, char*[],Shbltin_t*);
@@ -182,10 +176,8 @@ extern const char sh_opthist[];
 #endif /* !SHOPT_SCRIPTONLY */
 extern const char sh_optjobs[];
 extern const char sh_optkill[];
-#if defined(JOBS) && defined(SIGSTOP)
 extern const char sh_optstop[];
 extern const char sh_optsuspend[];
-#endif /* defined(JOBS) && defined(SIGSTOP) */
 extern const char sh_optksh[];
 extern const char sh_optlet[];
 extern const char sh_optprint[];

src/cmd/ksh93/include/jobs.h

@@ -2,7 +2,7 @@
 *                                                                      *
 *               This software is part of the ast package               *
 *          Copyright (c) 1982-2011 AT&T Intellectual Property          *
-*          Copyright (c) 2020-2022 Contributors to ksh 93u+m           *
+*          Copyright (c) 2020-2023 Contributors to ksh 93u+m           *
 *                      and is licensed under the                       *
 *                 Eclipse Public License, Version 2.0                  *
 *                                                                      *
@@ -32,27 +32,17 @@
 #endif /* !SIGINT */
 #include	"FEATURE/options"
 #include	<aso.h>
+#include	"terminal.h"
 
-#undef JOBS
-#if defined(SIGCLD) && !defined(SIGCHLD)
-#   define SIGCHLD	SIGCLD
+#ifndef SIGCHLD
+#   error ksh 93u+m requires SIGCHLD
 #endif
-#ifdef SIGCHLD
-#   define JOBS	1
-#   include	"terminal.h"
-#   ifdef FIOLOOKLD
+#ifdef FIOLOOKLD
 	/* Ninth edition */
 	extern int tty_ld, ntty_ld;
 #	define OTTYDISC	tty_ld
 #	define NTTYDISC	ntty_ld
-#   endif	/* FIOLOOKLD */
-#else
-#   undef SIGTSTP
-#   undef SH_MONITOR
-#   define SH_MONITOR	0
-#   define job_set(x)
-#   define job_reset(x)
-#endif
+#endif /* FIOLOOKLD */
 
 struct process
 {
@@ -67,10 +57,8 @@ struct process
 	unsigned short	p_exitmin;	/* minimum exit value for xargs */
 	unsigned short	p_flag;		/* flags - see below */
 	unsigned int	p_env;		/* subshell environment number */
-#ifdef JOBS
 	off_t		p_name;		/* history file offset for command */
 	struct termios	p_stty;		/* terminal state for job */
-#endif /* JOBS */
 };
 
 struct jobs
@@ -90,10 +78,8 @@ struct jobs
 	int		numbjob;	/* number of background jobs */
 #endif /* SHOPT_BGX */
 	short		fd;		/* tty descriptor number */
-#ifdef JOBS
 	int		suspend;	/* suspend character */
 	int		linedisc;	/* line discipline */
-#endif /* JOBS */
 	char		jobcontrol;	/* turned on for interactive shell with control of terminal */
 	char		waitsafe;	/* wait will not block */
 	char		waitall;	/* wait for all jobs in pipe */
@@ -109,8 +95,6 @@ struct jobs
 
 extern struct jobs job;
 
-#ifdef JOBS
-
 #if !_std_malloc
 #include <vmalloc.h>
 #ifdef vmlocked
@@ -144,14 +128,11 @@ extern const char	e_access[];
 extern const char	e_terminate[];
 extern const char	e_no_jctl[];
 extern const char	e_signo[];
-#ifdef SIGTSTP
-   extern const char	e_no_start[];
-#endif /* SIGTSTP */
+extern const char	e_no_start[];
 #ifdef NTTYDISC
    extern const char	e_newtty[];
    extern const char	e_oldtty[];
 #endif /* NTTYDISC */
-#endif	/* JOBS */
 
 /*
  * The following are defined in jobs.c
@@ -168,18 +149,12 @@ extern void	job_subrestore(void*);
 #if SHOPT_BGX
 extern void	job_chldtrap(int);
 #endif /* SHOPT_BGX */
-#ifdef JOBS
-	extern void	job_init(int);
-	extern int	job_close(void);
-	extern int	job_list(struct process*,int);
-	extern int	job_hup(struct process *, int);
-	extern int	job_switch(struct process*,int);
-	extern void	job_fork(pid_t);
-	extern int	job_reap(int);
-#else
-#	define job_init(flag)
-#	define job_close()	(0)
-#	define job_fork(p)
-#endif	/* JOBS */
+extern void	job_init(int);
+extern int	job_close(void);
+extern int	job_list(struct process*,int);
+extern int	job_hup(struct process *, int);
+extern int	job_switch(struct process*,int);
+extern void	job_fork(pid_t);
+extern int	job_reap(int);
 
 #endif /* !JOB_NFLAG */

src/cmd/ksh93/sh.1

@@ -6948,8 +6948,7 @@ option or by name with the
 option
 (as given in
 .BR <signal.h> ,
-stripped of the prefix ``SIG'' with
-the exception that SIGCLD is named CHLD).
+stripped of the prefix ``SIG''.
 For backward compatibility, the
 .B n
 and